The present invention relates to a band setting apparatus for suppressing cell delay variations in a transmission apparatus for performing TDMA (Time Division Multiple Access) communication on the cell base, in which a station device and a plurality of remote devices are star-connected, and band setting management for the remote devices is performed by the station device.
Conventionally, a transmission apparatus for performing TDMA communication on the cell base has been provided, in which a plurality of remote devices are star-connected to a station device, and band setting management for the remote devices is performed by the station device. In this transmission apparatus, the service quality to be provided to the remote devices is guaranteed by suppressing cell delay variations. In addition, to cope with a case in which different bands are assigned to the remove devices depending on the provided service, the number of cells in units of band management frames for the first remote device is uniformly set in a band setting table on which the cells are actually assigned, and the number of cells in units of band management frames for the next remote device is uniformly set in the band setting table on which the cells are actually assigned. This processing is repeated, and if a setting position overlaps the previous setting position, the setting position is shifted backward to set a new band.
In "Apportionment of Upstream Bandwidth for ATM-PDS System", Proceedings of the 1996 IEICE Communication Society Conference, B838, 1996, a method of obtaining an ideal cell sending timing signal by using a counter or the like to weight a cell for a remote device with a sending delay has been proposed because when the cell assignment positions overlap, the cell variation becomes large.
In the transmission apparatus for performing TDMA communication on the cell base, in which a plurality of remote devices are star-connected to a station device, and band setting management for the remote devices is performed by the station device, one of the necessary conditions for guaranteeing the quality of services to be provided to the remote devices is to suppress cell delay variations. In some cases, different bands are assigned to the remove devices depending on the provided service (for example, a band in the range of 1 to N cells per band setting management frame is arbitrarily assigned to each remote device). For this reason, a band setting algorithm which allows the station device to automatically execute optimum band setting must be prepared.
In the conventional transmission apparatus, cell delay variations in band setting for the first remote device pose no problem. However, in a remote device for which band setting is performed later, the cell delay variations become larger, so the service quality cannot be guaranteed. In the method of calculating the cell sending timing by weighting delayed cells, the cells are not sent unless they are weighted, so the cell delay variations may become large. This method is unsuitable to manage the service quality in units of remote devices because the cell sending timing is not output in units of remove devices.